1. Field of the Invention
This invention relates to a grain silo which is high in gas-tightness, liquid-tightness and durability and in which no charging phenomenon occurs in an inner wall surface of the silo.
2. Prior Art
As is well known, a silo has such various advantages that it is remarkably high in storage capacity, is reasonable in construction or structure, is easy in building, is easy in introduction and discharge of contents, and can prevent the contents from being changed in quality, as compared with a usual warehouse or storehouse. Therefore, the silo has been utilized as important, central facilities, for storing not only grain or cereals, but also industrial materials such as, for example, coal, sand, gravel, cement, ore, manure, common salt and the like.
In order to store the above-noted materials in a most effective manner, it is necessary that such silo has a wall thereof made of an air and moisture impermeable material and has a wall surface finished smoothly, to sufficiently insulate the material from the air. That is, it is required for the silo to secure high gas-tightness and liquid-tightness for a long period of time.
The construction or structure of the silo is broadly divided into three kinds, i.e., iron plate structure, iron plate/concrete structure and reinforced concrete structure.
Of the above three structures, both the iron plate structure and the iron plate/concrete structure exhibit satisfactory performance in gas-tightness and liquid-tightness, though the iron plate structure has such a disadvantage that it is lacking in ability of heat insulation. On the other hand, the reinforced concrete structure has such a problem that cracks are developed in the wall with the lapse of time which injure the gas tightness and liquid-tightness, though the reinforced concrete structure is manufactured at low cost and is superior in heat insulation. Heretofore, attempts have been made to resolve the problem by the provision of a wall surface protective layer or layers such as, for example, epoxy resin lining layers, fiber reinforced plastic (FRP) lining layer, an iron plate lining layer or the like, on an inner wall surface of an wall body of the silo of the reinforced concrete structure. The epoxy resin lining layers are formed by the successive coating and laminating of the whole or a part of a plurality of coating layers such as a primer or under coating, paste, resin mortar, main coating, finish or top coating and the like, each of which has blended therein epoxy resin.
However, the above-described conventional silo, i.e., the silo of such structure that the wall surface protective layer or layers such as multi-layer epoxy resin lining layers, FRP lining layers, iron plate lining layer or the like is or are provided on the inner wall surface of the silo wall body, has such disadvantage that the inner wall surface is liable to be or tends to be charged and there would be a risk of dust explosion in case where a material stored is a powder material such as wheat flour (for the epoxy resin lining layers and the FRP lining layers), the initial cost is high and there is no applicability to repair works of the existing silo of the reinforced concrete structure (for the iron plate lining layer), and the like.